Nagasaki Castella: A Sponge Cake With Portuguese Roots

A moist, honey-sweet cake that sailed in with Portuguese traders and settled into Nagasaki's gift shops.

Published October 18, 2026 at 8:27 PM JST | By Tokyo Paul

Quick answer: Castella, called kasutera in Japanese, is a moist, fine-textured sponge cake made from eggs, sugar, flour and honey or syrup. It came to Japan with Portuguese traders in the sixteenth century and is strongly associated with Nagasaki. Traditional loaves have a golden top and a layer of crunchy sugar crystals on the bottom, and they are a popular souvenir.

A Cake With Portuguese Roots

Castella reached Japan in the sixteenth century, when Portuguese traders and missionaries arrived at Nagasaki and other southern ports. The name is thought to come from a Portuguese phrase referring to bread from Castile. Over time, Japanese bakers adapted the recipe, shaping it into a distinct sweet. Early Japanese bakers adjusted the recipe to suit local taste, using ingredients such as sugar and eggs, which were precious at the time.

The cake is made with simple ingredients: eggs, sugar, flour and a sweetener such as honey or starch syrup. There is typically no butter or oil, which gives it a clean, light flavor. The batter is whisked to incorporate air and baked slowly, producing a fine, even crumb. Because the batter is so simple, the quality of the eggs and the baking skill matter more than elaborate flavoring.

Nagasaki has long been a gateway to the outside world, and its cuisine shows this influence. Castella stands among the dishes that reveal foreign contact blending with local craft. The cake is now so integrated that many people consider it a traditional Japanese sweet, enjoyed with tea. Dutch and Chinese traders also settled there, and the city shows that mix in its food, architecture and festivals.

What Makes the Texture Special

A good castella is moist, springy and slightly dense, with a tender crumb. The top has a thin golden-brown crust, and the interior is pale yellow. The sweetness is gentle and honeyed, and the flavor of eggs is clear. Each slice feels soft but holds its shape. A slice held up to the light often shows a fine, even structure with small, evenly spaced air pockets.

At the bottom, many traditional loaves have a layer of coarse sugar crystals, called zarame. These crystals give a pleasant crunch and a caramel-like sweetness. Some people pick at the bottom layer first, while others save it for the end. It is a small pleasure that characterizes Nagasaki-style castella. Machine-baked loaves from large makers often leave out the crystals for a smoother base.

The cake is baked in a rectangular wooden frame, which helps it rise evenly. Bakers rotate the batter by hand during baking to release bubbles. This careful technique takes practice and is part of why handmade castella commands respect. Machine-baked versions are available too and are often more affordable. Large kitchens use special ovens, while small shops may still do much of the work by hand.

Famous Shops and Gift Culture

Nagasaki is home to several long-established castella shops, some of which have operated for centuries. Their boxes are recognized across Japan, and visitors often buy them as gifts for family and colleagues. The elegant packaging adds to the sense of occasion. Many shops stand within a short walk of the tram line, which makes a tasting walk easy to plan.

Castella is a standard omiyage, or travel souvenir. Nagasaki's boxes come in different sizes, from small packs to large loaves. Shops often sell pre-cut slices wrapped individually, convenient for sharing in an office. Gift boxes may include a mix of flavors. Individually wrapped slices are particularly useful for office gifts, because no cutting is needed.

Because each shop has its own recipe, taste and texture differ. Some are sweeter, some lighter, some more eggy. Trying samples, which many shops offer, helps you choose. Check each shop's official site for hours and shipping options, since some offer delivery to other parts of Japan. Notes on the box about egg content, honey or sugar help you compare.

Flavors and Variations

Beyond the classic version, castella appears in many flavors. Matcha, brown sugar, chocolate and honey variations are common. Seasonal editions may feature chestnut or fruit. Some shops offer castella with a swirl of bean paste or cream, though purists prefer the original. Limited editions appear for holidays and are often sold only in the shop where they were made.

Other variations include bite-size castella, castella sandwiches and castella-based desserts. In recent years, fluffy Taiwanese-style castella has become popular in cafes, offering a different texture. Each version has its fans. Cafes also serve castella French toast, which is a fun way to use a day-old loaf.

In Nagasaki, you may also find castella served in cafes with tea or coffee. It is a simple treat that fits any time of day. If you enjoy experimenting, compare two shops' versions side by side, and note the differences in sweetness and moisture. A slice at a cafe is a good way to try the cake before buying a whole loaf.

Visiting Nagasaki

Nagasaki is on the island of Kyushu. Visitors can reach it by air, with Nagasaki Airport serving major cities, or by train from Fukuoka's Hakata Station on the limited express line, which takes roughly two hours or so. Check timetables on official sites for current options. Trains from Hakata run frequently, and airport buses connect Nagasaki Airport with the city center.

The city is hilly and compact, with an efficient tram network that covers many attractions. Dejima, the former Dutch trading post, Chinatown, Glover Garden and the harbor are within easy reach. Many castella shops are near the central areas, making them convenient stops. Comfortable shoes are a good idea, as the streets include slopes and steps.

Nagasaki also offers other local foods such as champon noodles, sara udon and Turkish rice. Planning a day of tasting local dishes is rewarding. Evenings bring harbor views and night illuminations in some seasons. Allow time for walking and sightseeing at a relaxed pace. Champon is a noodle soup with seafood and vegetables, and sara udon features crispy noodles topped with a thick sauce.

Storage, Cutting and Serving

Castella keeps well compared with many cakes because of its dense, moist crumb. Store it in its wrapper at room temperature, away from sun and heat. Many shops advise eating within several days, though exact times vary. Check the label for guidance. Do not store it near strong smells, as the cake can absorb them.

When cutting, use a long, sharp knife and a gentle sawing motion to avoid crushing the loaf. Some bakers use a thread to slice cleanly. Cut slices about two centimeters thick. Leave the sugar crystals at the bottom, and serve the cake on a small plate. Warm the blade briefly in hot water and wipe it dry for a cleaner cut.

For a lovely touch, warm a slice slightly or serve at room temperature. Avoid refrigeration if possible, as it can dry the cake. If you must refrigerate, wrap tightly and let it return to room temperature before eating. A short rest at room temperature before serving also makes the texture softer.

Pairings and Common Mistakes

Castella pairs naturally with green tea, black tea or coffee. The cake's gentle sweetness balances the bitterness of matcha and sencha. A little whipped cream or fruit makes a pleasant dessert, though many people enjoy it plain. The cake is rich in egg, so a pot of tea offers a clean counterpoint.

A common mistake is slicing it too thin, which makes it crumble. Another is leaving it unwrapped, causing it to dry out. Keep it covered and store properly. When buying as a gift, check the best-by date to ensure freshness on arrival. A thickness of about two fingers works well and shows off the texture.

Avoid assuming that all castella is overly sweet. Many versions are balanced, with a focus on egg flavor. Taste with an open mind, and choose according to your preference. Shops are used to questions and happy to help. Taste a small piece before you buy a large box, if samples are offered.

Frequently Asked Questions

What is castella?

It is a sponge cake made from eggs, sugar, flour and honey or syrup, introduced to Japan by Portuguese traders and strongly associated with Nagasaki.

What are the crunchy crystals at the bottom?

They are coarse sugar crystals called zarame, added for texture and sweetness. They are a traditional feature of many loaves.

How long does castella keep?

It keeps for several days at room temperature when wrapped, but check the label for specific guidance.

Keep Exploring

More guides from Tokyo Paul: Dejima: Nagasaki's Dutch Trading Post, Konpeito: The Tiny Sugar Stars With a Portuguese Past and Glover Garden: Nagasaki's Hillside Western Houses.